This invention relates to the field of video imaging and, more specifically, to a video imaging apparatus for use in dental imaging.
Video imaging cameras have been used for obtaining images in dentistry for some time. One example of an existing system can be found in U.S. Pat. No. 5,523,782 (Williams), which describes a video dental camera that includes a light source, a CCD, and an adjustable focus lens system. Other examples of existing system can be found in U.S. Pat. No. 4,575,805 (Moermann et al.), and in U.S. Pat. No. 5,527,261 (Monroe et al.).
Until now, however, it has been extremely difficult to fashion a sufficiently slim instrument. Slim instruments are desirable because they provide accessibility to places that thicker instruments can not reach. Moreover, even in cases where a thick instrument can provide adequate access, the slimmer instruments can reduce the discomfort experienced by the patient.
One factor contributing to the thickness of previous dental video cameras is the type of light source that is incorporated into the camera head. Some previous dental cameras, such as the one described in U.S. Pat. No. 5,429,502, use an external light source and route the light from the source to the head using fiber optics. This arrangement, however, requires the optical fibers to travel through the cable and through the body of the handheld camera unit, which results in a stiffer cable (which can reduce maneuverability) and a thicker handheld unit. In addition, the fiber optic connections require a more complex and expensive connector, as compared to fully electrical connectors. Finally, using fiber optics to illuminate the subject requires increased power, because some of the light energy is lost in the optical fiber.
Other prior art imaging devices use lamps at the end of the imaging head instead of fiber optics. But until now, lamps have not been used in configurations that minimize the thickness of the instrument. For example, the lamps in Williams are positioned axially away from the imaging window, and the lamp in Moermann is positioned on the proximal side of the imaging window. Both of these configurations result in relatively thick instruments.
In addition, the lamps used in previous imaging devices had significant shortcomings. One example is the halogen lamp used in Monroe, which consumes significant power and generates heat. Another example is the LED used in Moermann, which, like all ordinary LEDs, produces essentially monochromatic light that can make diagnosis of certain medical conditions difficult.